Libyan rebels welcomed President Obama’s deployment of armed Predator drones and received praise from their most prominent U.S. visitor Friday, as they expressed hope that increased American support would help turn the tide in a conflict that the top U.S. military officer acknowledged is becoming deadlocked.

Sen. John McCain (R-Ariz.), an early proponent of helping the rebels in their fight against forces loyal to longtime leader Moammar Gaddafi, arrived Friday in Benghazi, the de facto rebel capital in eastern Libya, and told reporters that the anti-Gaddafi fighters are his heroes.

The previously unannounced visit came a day after the U.S. military sent the first two Predators to Libya but had to cut short their mission because of bad weather. McCain, the top Republican on the Senate Armed Services Committee, said he was meeting with members of the Transitional National Council, the rebel government in Benghazi, to assess the situation. As he left a hotel in the city with a security detail, he said of the rebels, “They are my heroes,” the Associated Press reported.

In Baghdad, meanwhile, Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, conceded that the conflict in Libya is “certainly moving towards a stalemate,” even though he said airstrikes by U.S. and allied warplanes have reduced Gaddafi’s ground forces by “somewhere between 30 and 40 percent.”

Speaking to U.S. troops during a visit to the Iraqi capital, Mullen said the capabilities of those ground forces “will continue to go away over time,” Reuters news agency reported. Ultimately, he said, “Gaddafi’s gotta go,” and coalition actions “are going to continue to put the squeeze on him until he’s gone.” But he said it was unclear how long that would take. “Is he going to figure that out? I don’t know,” Mullen said.

Mullen also said the United States is watching for any al-Qaeda involvement in the Libyan opposition but has not detected anything significant. “In fact, I’ve seen no al-Qaeda representation there at all,” he said.

Responding to the U.S. decision to deploy Predators, Benghazi-based rebel spokesman Abdul Hafidh Ghoga told al-Jazeera television: “There’s no doubt that will help protect civilians, and we welcome that step from the American administration.” Other rebels made similar comments.

The deployment deepened U.S. involvement in the stalemated conflict and once again put U.S. assets into a strike role against loyalist ground forces.

The U.S. military will continue to maintain at least two Predators over Libya at all times, officials said Thursday.

At a news conference, Defense Secretary Robert M. Gates was adamant that the use of the drones was not a prelude to an even deeper U.S. commitment involving more strike aircraft or U.S. ground troops. “I think the president has been firm, for example, on boots on the ground,” he said. “There is no wiggle room in that. . . . This is a very limited capability.”`

Armed drones are in heavy demand in places such as Afghanistan, Pakistan and Yemen, and the announcement of their deployment to Libya seemed designed at least in part to send a message to Gaddafi that the United States remains invested in the conflict.

It also served as a demonstration of U.S. resolve to European allies, who have been pressing for greater involvement by the U.S. military in the weeks since it took on a supporting role in the mission.

Rebel forces in eastern Libya have failed to maintain advances from their Benghazi base and forward positions at the crossroads town of Ajdabiya. Their major prize in western Libya, Misurata, has come under relentless barrages from Libyan army artillery and rocket launchers, causing rebel leaders to plead for intervention by foreign ground troops.

On Thursday, rebels in Misurata were buoyed by news that armed drones had been deployed to the region. “It is wonderful news,” a rebel spokesman said.

He said that NATO airstrikes had helped drive loyalist forces back in the last couple of days. “It is still very desperate but not so bleak. There is some hope after these victories,” said the spokesman, who declined to be identified for fear of retribution.

The armed Predators’ first mission over Libya was cut short Thursday because of bad weather. The unmanned aircraft can stay over an area for upwards of 12 hours at a stretch, making them much better at distinguishing rebel troops from loyalist forces than faster-moving fighter jets, which also must stay at higher altitudes.

Predators carry relatively small Hellfire missiles that are much more effective than precision guided bombs at striking enemy troops in heavily populated urban areas.

In recent weeks the sustained NATO airstrikes have driven Gaddafi’s forces to seek the protection of cities, where it has been more difficult to strike them without causing civilian deaths. The drones could open up targets there were previously off-limits to NATO aircraft.

“The character of the fight has changed,” said Gen. James Cartwright, the vice chairman of the Joint Chiefs of Staff. “You are seeing . . . people that are digging in or nestling up against crowded areas, where collateral damage is’’ a concern.

Libyan officials condemned the use of the drones as a violation of the U.N. Security Council resolution that authorized intervention in Libya for the sole purpose of protecting civilians.

“On the contrary, they will kill more civilians, and this is very sad,” Deputy Foreign Minister Khaled Kaim told reporters in Tripoli. “What they are doing is undemocratic, illegitimate, and I hope they will reverse their decision.”

Both Britain and France have clearly stated that a major focus of the air campaign is to destroy Gaddafi’s military and weaken his grip on power. By their yardstick — helping rebel forces topple Gaddafi — the bombing campaign has fallen short.

No one inside the U.S. military expects that the Predators by themselves will be enough to break the stalemate between loyalist and rebel forces in Misurata or other key Libyan cities.

But Thursday, Gates, who had expressed deep skepticism about intervening in Libya, struck a somewhat optimistic note about the progress of the bombing campaign. The sustained strikes were slowly eroding Gaddafi’s ground forces. “Day after day, the capabilities of his military are being reduced,” Gates told reporters.

The U.N.-backed sanctions on the Libyan regime will over time prevent Gaddafi from replenishing his ammunition stocks, paying his soldiers and hiring mercenaries, Gates predicted. “That’s not a short-term thing,” he said. “But the fact is that it is taking place day after day. We’ll just have to see. This is an uncertainty.”

Some European officials have lamented the absence of U.S. A-10 Warthog ground-attack jets — specifically designed for close air support — and AC-130 gunships. While the low- and slow-flying planes were deployed in small numbers during the first two weeks of the campaign, they were rarely used because of fears they would be shot down by the Libyan army.

The Predators can fly at low altitudes without putting a pilot at risk. Last month Gates said that the Air Force was able to maintain about 48 Predators around the world at any given time.

In Afghanistan, the drones are flying long hours along the Afghanistan-Pakistan border in an effort to spot Taliban fighters who are moving back into Afghanistan for the upcoming fighting season. Gates said that no drones have been shifted from Afghanistan.

Separately, State Department officials Thursday acknowledged delays in releasing $25 million in U.S. aid to the Libyan rebels. The decision to provide the non-lethal support — including vehicles, boots and body armor — was announced Wednesday to address what U.S. officials had described as an urgent need.

But State Department spokesman Mark Toner said the White House had not yet signed off on releasing the equipment.

“We’re trying to meet their needs in a coherent and appropriate way,” Toner said. “We don’t want to give them things they don’t necessarily need.”

William Branigin writes and edits breaking news. He previously was a reporter on the Post’s national and local staffs and spent 19 years overseas, reporting in Southeast Asia, Central America, the Middle East and Europe.

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